Concrete ceiling slab form installation and dome-supporting shore assembly therefor

ABSTRACT

A supporting shore for a concrete ceiling slab, having a vertically and downwardly shiftable rotatable member which normally supports the adjacent truncated four corners of a quadrilaterally arranged group of four inverted generally rectangular pan-shaped slab-supporting domes and which, in the lowered and rotated position of the member, moves out of operative register with two of the four corners so as to release the other two corners for dome-removal purposes, while at the same time the shore continues to support the concrete ceiling slab until the latter has become fully hardened.

States Patent Pipaia Mar. 7, 1972 CONCRETE CEILING SLAB FORM INSTALLATION AND DOME- SUPPORTING SHORE ASSEMBLY THEREFOR lnventor: Dennis R. Pipala, Park Ridge, Ill.

Assignee: Symons Corporation, Des Plaines, 111.

Filed: Jan. 15, 1970 Appl. No.: 3,061

US. Cl. ..249/3l, 248/354, 25/ 13 1.5 A, 249/194, 249/18 Int. Cl ..E04g 11/40 Field oiSearch ..249/192, 193, 194, 177,142,

[56] References Cited UNITED STATES PATENTS 2,734,250 2/1956 Thompson ..249/177 X 3,430,910 3/1969 Bowden et al. "249/192 X Primary Examiner-J. Spencer Overholser Assistant Examiner-DeWalden W. Jones Attorney-Norman H. Gerlach [5 7] ABSTRACT A supporting shore for a concrete ceiling slab, having a vertically and downwardly shiftable rotatable member which normally supports the adjacent truncated four corners of a quadrilaterally arranged group of four inverted generally rectangular pan-shaped slab-supporting domes and which, in the lowered and rotated position of the member, moves out of operative register with two of the four comers so as to release the other two comers for dome-removal purposes, while at the same time the shore continues to support the concrete ceiling slab until the latter has become fully hardened.

5 Claims, 9 Drawing Figures PATENTEUMAR 1 m2 3.647, 173

SHEET 1 [IF 4 INVENTOR DENNIS R. PIPALA 'mma Attorney PATENTEDMAR 7 I972 3, 647, 173

SHEEI 2 BF 4 INVENTOR DENNIS R. PIPALA Attorney PATENTEDMAR 7 I972 3.647, 173

, INVENTOR DENNIS R. PIPALA PATENTEDMAR' 1 m2 SHEET l UF 4 INVENTOR DENNIS R. PIPALA Attorney CONCRETE CEILING SLAB FORM INSTALLATION AND DOME-SUPPORTING SHORE ASSEMBLY THEREFOR The present invention relates generally to concrete building construction and has particular reference to a novel shore assembly which is designed for use in releasably supporting the four adjacent corners of a series of four quadrilaterally arranged ceiling slab-supporting domes preparatory to and during a concrete pouring operation, as well as after the concrete has been poured and up until such time as the concrete has become sufficiently set or hardened that it is considered safe to remove the domes. Specifically, the shore assembly of the present invention is of the general type which is illustrated and described in U.S. Pat. No. 3,340,910, granted on Mar, 4, 1969 and entitled STRINGER-RELEASING SHORE ASSEMBLY FOR A CONCRETE SLAB FORM INSTALLATION. Whereas the shore assembly which is disclosed in such patent is designed normally to support adjacent ends of horizontally extending, longitudinally aligned stringers which in turn serve to support a series of horizontal slab-supporting panels and to release such stringers after the concrete which is poured upon the panels has become hardened to such an extent that the stringers and panels are no longer considered essential for slab supporting purposes, the present shore assembly differs from the patented shore assembly in that it is specifically designed for use in a concrete ceiling slab form installation which is devoid of stringers and panels and, instead, employs a series of inverted pan-shaped members which are preferably formed of a suitable plastic material and are arranged in checkerboard fashion so that each series of four adjacent members are disposed in quadrilateral relationship. Such pan-shaped members are known in the industry variously as pans" or domes, the latter designation being employed herein in the interest of consistency.

The dome-supporting and releasing shore assembly of the present invention is similar in its purpose to that of aforementioned U.S. Pat. No. 3,430,910 in that it serves to support a series of ceiling slab-supporting members. It differs, however, from the patented shore assembly in that the slab-supporting members, instead of being panel-supporting stringers, are the aforementioned domes, and also in that instead of releasably supporting the adjacent ends of a pair of aligned stringers, it supports the aforementioned four adjacent corners of the quadrilaterally arranged series of domes. As will become apparent as the nature of the invention is better understood, temporary support and subsequent release of such four corners without destroying the slab-supporting function of the shore assembly poses a problem of dome clearance by the shore assembly during the time that the domes are lowered away from the hardened concrete ceiling-forming slab which has been poured around the outer surfaces of the domes and the solution of this problem constitutes the principal feature of the present invention.

It is here pointed out that the stringer-releasing shore assembly of U.S. Pat. No. 3,430,910 was designed to extend or increase the usefulness of a system of building erection which is disclosed in and forms the subject matter of U.S. Pat. No. 3,130,470, granted on Apr. 28, 1964, and which is known in the industry as a Slab-Shore System. The present dome-supporting and releasing shore assembly similarly is designed further to extend the usefulness of such Slab-Shore System in that slab-supporting domes are permitted early release from the installation as soon as the concrete of the ceiling-forming slab has become sufficiently hardened that the shore assembly alone will afford a safe support for the slab and so that the domes may be put to use in furthering the erection of a building while the concrete of the slab continues to harden to the point where the shore assembly itself may be removed.

The provision of a dome-supporting and releasing shore assembly such as has briefly been outlined above constitutes the principal object of the invention. In carrying out this object, the shore assembly of the present invention embodies droptype ledgelike supports which normally support adjacent corners of the quadrilaterally arranged domes prior to and during concrete pouring operations around the outer surfaces of the domes. After the concrete has been poured and has become hardened to such a degree that the domes are no longer necessary for the overall support of the concrete ceiling-forming slab, means are provided whereby these ledgelike supports may be lowered away from the domes while the upper end of the shore assembly continues to support the slab. The domes may then be lowered away from the thus supported slab, and in order to afford a clearance region so as not to interfere with further downward movement of the domes for complete removal thereof from the installation, additional means are provided whereby the ledgelike supports may be rotated to an out-of-the-way position with respect to the adjacent corners of the set of four quadrilaterally arranged domes, to the end that the domes may then be tilted out of their normal horizontal positions and caused to pass beneath the supports for complete removal from the installation, all in a manner that will be described in detail hereafter.

Numerous other objects and advantages of the invention, not at this time enumerated, will become readily apparent as the nature of the invention is better understood.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by the claims at the conclusion hereof.

In the accompanying four sheets of drawings forming a part of this specification, one illustrative embodiment of the invention is shown.

In these drawings:

FIG. 1 is a fragmentary top perspective view of a dome-type concrete ceiling slab installation, showing a number of the improved dome-supporting and releasing shore assemblies of the present invention operatively installed therein, certain of the shore assemblies being shown in dome-supporting relationship and others being shown in dome-releasing relationship;

FIG. 2 is an enlarged perspective view of one of the improved dome-supporting and releasing shore assemblies, such assembly being shown in its dome-supporting relationship adjacent to the juncture region between four quadrilaterally arranged domes, one of the domes being omitted in the interest of clarity;

FIG. 3 is an enlarged exploded perspective view of the dome-supporting and releasing shore assembly of FIG. 2, the ledgelike supports of the assembly being disposed in their operative or normal supporting relationship;

FIG. 4 is a side elevational view of the assembly of FIGS. 2 and 3, the assembly being shown with the dome-supporting ledgelike supports in their lowered position in order to release the superjacent domes;

FIG. 5 is a vertical or longitudinal sectional view taken on the line 5-5 of FIG. 4 and showing the assembly in its operative slab and dome-supporting relationship;

FIG. 6 is an exploded perspective view of the two-part separable supporting clamp arrangement which is employed in connection with the invention and forms a part of the improved dome-supporting and releasing shore assembly;

FIG. 7 is a perspective view of the filler plate which is employed in connection with the invention and forms a part of the improved dome-supporting and releasing shore assembly;

FIG. 8 is an enlarged horizontal sectional view taken on the line 8-8 of FIG. 4; and

FIG. 9 is an enlarged horizontal sectional view taken on the line 9-9 of FIG. 5.

Referring now to the drawings in detail and in particular to FIG. I wherein a concrete ceiling slab installation employing dome-supporting and releasing shore assemblies of the present invention is illustrated and designated in its entirety by the reference numeral 10, the various shore assemblies 12 are disposed vertically and are laterally spaced throughout the installation. In the interest of brevity, these assemblies 12 will hereinafter be referred to simply as "shores. The upper end region of each of the illustrated shores serves normally to support the four converging or adjacent corner regions of a series of four quadrilaterally arranged slab-supporting domes I4, the

support for such comer regions being in the form of a dropshoulder device or cradle member 16. Each shore also serves by means of a filler plate 18 at its extreme upper end to support the concrete which is poured around the outer surfaces of v the various domes 14 and which, upon hardening thereof, becomesthe ceiling slab S (see FIGS. 4 and 5) which is to be formed.

The individual domes 14 resemble conventional domes in that they are of inverted pan shape construction. However, the domes 14 differ from such conventional domes in that they are provided with special rim flanges and with mitered or truncated corner regions as will appear presently. Each dome comprises a flat rectangulardome panel which preferably is square and from the marginal edges of which there depends a series of four trapezoidal sidewalls 22. Rim flanges'24 project laterally and outwards from the lower edges of the sidewalls 22 and the outer edges of these rim flanges are turned downwardly to provide depending marginal apron flanges 26. Portions of the rim flanges 24 and the depending marginal flanges 26 are omitted and filled in with short 45 filler flanges 28, thus establishing a series of four truncated comers for each dome as a whole. In the illustrated form of dome 14, the sidewalls 22 slope downwardly and outwardly at a small angle although, if desired, these sidewalls may lie in vertical planes.

The dome-supporting and releasing shore 12 of the present invention involves in its general organization an adjustable base part which consists of any desired number of telescopic tubular sections, two such sections being shown at 30 and 32, and, in addition, an upper part in the form of a shore head 34. The shore head 34 is inclusive of the aforementioned filler plate 18 and the drop-shoulder device 16, the latter being in the form of a rotatable and vertically movable cradle member. The shore head 34 further includes an upper rotatable tubular body portion 36 and a lower nonrotatable inner post section 38 which, in effect, constitutes an upper shore section in that it seats upon the upper section 32 of the base part. The upper end region of the post section 38 is provided with an external screw thread 40 (see FIG. 5) which makes mating engagement with an internal screw thread 42 on the inner surface of the body portion 36 of the shore head 34. The upper portion of the post section 38 is of slightly increased diameter so that when the post section is threaded into the rotatable tubularbody portion 36 an appreciable distance there will be an overhang of the internal screw thread 42, thus establishing on the body portion a depending cylindrical apron 44 which encompasses and is slightly spaced from the cylindrical sidewall of the post section 38. The lower end of the post section 38 is formed with a reduced pilot portion 46 (see FIG. 5) which projects into the upper end of the shore section 32 and establishes a downwardly facing shoulder 48. The latter seats on the upper rim of said upper shore section 32. A hole 50 in the pilot portion 46 of the post section 38 registers with a hole 52 in the upper section 32 and both of these holes are adapted, when in register with each other, to receive therein a pin 54 which prevents relative turning movement of the post section 38 and the upper section 32. From the above description, it will be readily apparent that by rotating the body portion 36 of the shore head 34 in one direction or the other with respect to the fixed post section 38, elongation or shortening, as the case may be, of the shore 12 as a whole may be effected.

The upper end of the body portion 36 of the shore head 34 is provided with a circular combined end closure and bearing plate 60 (see FIG. 5), the rim portion of which extends downwardly and overhangs the upper end of the body portion 36 as indicated at 61 for a purpose that will be made clear presently. A vertically extending elevation post 62 has its lower end projecting through a hole 63 in the central portion of the plate 60 and is fixedly secured for rotation bodily with the body portion 36 by means of a horizontal bolt 64 which projects diametrically across the upper end of the body portion and passes through a hole in the lower end of the post 62. The upper end of-the post 62 is squared as indicated at 65 for reception of a suitable torque-applying tool such as a wrench by means of which the post, and consequently, the body portion 36, may be rotated as a unit, thus making it possible to effect a relatively fine adjustment of the height of the body portion for slab-leveling purposes, the adjustment being made by a workman operating from above the domes 14. A similar adjustment may also be made by a workman operating from ground level below the domes 14 by reason of a series of torque brackets 66 which are welded to the lower end regions of the body portion 36, these brackets being capable of cooperation with a suitable spanner wrench or the like. A circular bearing flange 68 on the elevation post 62 near the lower end thereof rests upon the combined end closure and bearing plate 60.

Still referring to FIG. 4, and additionally to FIGS. 2, 3 and 5, an open-ended tubular cylindrical housing 70 has its lower rim welded at 72 to the upper surface of the plate 60. The upper rim of the housing is adapted to receive thereover the slabsupporting filler plate 18 (see also FIG. 7). An X-shaped pilot grid 76 on the underneath side of the tiller plate 18 permits the plate to be positioned in a centered overlying position over the upper rim of the housing 70 so as to exclude the entrance of wet poured concrete into the latter. Upon removal of the tiller plate 118, access is provided to the upper square end 65 of the elevation post 62 for manipulation of the latter.

The cradle member 16 (drop-shoulder device) is of unitary construction and embodies welded parts including a central sleeve member 80 which encompasses and is both rotatable and vertically slidable on the tubular body portion 36, four triangular gusset webs 82 which project radially outwards from the opposite sides of the sleeve member 80, and two laterally projecting ledgelike supports 84 which are carried at the upper ends of the webs 82. These ledgelike supports 84 are adapted normally to receive thereon and support the adjacent corner regions of four adjacent domes 14 as shown in FIGS. 1 and 2 and, in order to insure retention of these corner regions thereon, each support 84 is provided with two upstanding posts 86 which underlie the adjacent domes and project behind the depending marginal flanges 26 of the domes.

The tubular central sleeve member 80 of the cradle member 16 loosely and rotatably surrounds the body portion 36 of the shore and is vertically shiftable thereon between the raised dome-supporting position in which it is shown in FIG. 5 and the lowered dome-releasing position in which it is shown in FIG. 4. The sleeve member 80 is adapted to be releasably supported in its elevated position by means of a two-part separable clamp arrangement 90, the details of which are clearly shown in FIG. 6. Such clamp arrangement comprises two arcuate counterpart sections Q2 and 94 at certain opposed ends thereof two mating ears 96 which are capable of being connected together by a nut and bolt assembly 98, and also having at their other opposed ends two mating ears 100 which are capable of being connected together by a conventional bolt and wedge assembly 102. The clamp arrangement thus constitutes a separable and removable collar device which is adapted to surround the body portion 36 immediately below the lower end of the sleeve member 80 when the latter is in its raised position and the lower edge of the clamp arrangement is supported on the upper edges of two arcuate reaction plates 104 which are welded to the surface of the body portion 36 in diametrically opposed relationship. Upon removal of the clamp arrangement 90 as shown in FIG. 4, the sleeve member 80 and its associated parts, as well as the entire dome-supporting cradle 16, will fall by gravity to the lower position thereof and come to rest upon shoulders which are formed or established by the upper edges of the reaction plates 104. In this lowered position of the dome-supporting cradle member 16, a clearance is established for downward movement of the domes .14 beneath the slab S and also the cradle member 16 is capable of being rotated throughout an angle of 45 so that the ledgelike supports 84 of the cradle member 16 move out of register with the truncated corners of the domes to allow for complete removal of the domes from the concrete ceiling slab installation, all in a manner that will be described in detail subsequently.

Considering now the operation of the herein described dome-supporting and releasing shore 12, the manner in which the shore of the present invention is manipulated to release the associated domes 14 from any given slab installation, for example, the installation of FIG. 1, is best illustrated in FIGS. 4 and 5 when taken in conjunction with FIG. 1. The disclosure of FIG. 5 represents the condition of one of the shores 12 when it is in its operative slab and dome-supporting position beneath a recently poured ceiling slab S and after the concrete has hardened sufficiently to justify removal of the domes 14 over which the concrete has been poured. As shown in FIGS. 1 and 5, each shore 12, when operatively installed in a ceiling slab form installation, serves to support the converging, juxtapositioned corner regions of four adjacent quadrilaterally arranged domes 14. Each of these four corner regions overlies one of the upstanding dome-retaining posts 86 and the lower edge of the associated filler flange 28 rests upon one of the ledgelike supports 84. The separable clamp arrangement 90 is in position on the tubular body portion 36 of the shore head 34 with its lower edge resting on the upper edges of the two reaction plates 104 in order that the central sleeve member 80 of the cradle member (drop-shoulder device) 16 is maintained in an elevated position, thereby maintaining the various domes 14 at slab level, i.e., with their panels 20 in slab-supporting relationship. The various shores l2 assume the abovedescribed condition prior to and during concrete pouring operations, as well as thereafter until such time as the condition of the concrete is such that it is considered safe to effect dome removal. Under favorable conditions, a 24-hour period may justify dome removal operations.

It will be obvious that upon lowering of each cradle member 16 of any given shore, all of the four corner regions of the associated quadrilaterally arranged domes which are supported thereby will be released by the shore for stripping from the ceiling slab which overlies the domes. Various methods of dome removal, utilizing a series of the present shores 12, may be resorted to, depending upon the preferences of the operator or operators. If desired, cradle member lowering operations on all of the shores 12 may be effected before any domestripping operations are resorted to, this being possible because the concrete-to-plastic bond between the slab and the domes is adequate to retain the domes in position beneath the slab, even though the domes be otherwise unsupported. Alternatively, cradle member lowering operations on four adjacent shores will release one dome for removal purposes, and thus, consecutive dome removal operations may be carried out by progressive manipulation of the various shores in this manner. For purposes of description, it will be assumed that consecutive shore manipulation involving four of the shores for individual shore release is initially accomplished, after which the domes may be pulled, as desired, from their adhering bond with the concrete slab.

In order to lower the cradle member 16 of any given shore 12, it is necessary merely to use impact force to separate the bolt and wedge assembly 22 from the mating ears 100, after which the nut and bolt assembly 98 may be loosened and the sections 92 and 94 separated to an extent sufficient to permit their removal from the central sleeve member 80 of the cradle member 16. With the clamp arrangement 90 thus removed, the cradle member 16 in its entirety will become lowered so that it rests upon the reaction plates 104 as previously described. The phenomenon of adhesion causes the associated domes 14 to remain elevated and in contact with the superjacent slab S while the posts 86 are withdrawn downwardly from their positions behind the depending marginal flanges 26 of the four associated domes 14.

After any given group of four adjacent shores 12 has been thus manipulated so as to shift the cradle members 16 from their elevated position to their lowered position, the dome 141 between the four shores may then be stripped from the ceiling slab S thereabove, but with the various cradle members 16 maintaining their original orientation, the operator is unable to pass the released dome downwardly beyond the general level of the cradle members. The range of vertical movement of which the cradle members are capable is not adequate to permit tilting of the dome for sidewise or cornerwise removal since the edges of the dome will not clear the cradle members even when the allowable maximum tilting of the dome takes place.

To remedy this situation, the various cradle members 16 are rotatable on the tubular body portions 36 of the shore heads 34 so that by turning a given cradle member through an angle of 45 to shift its ledgelike supports 84 from positions of seam line register wherein these supports underlie the converging truncated comers of one group of four quadrilaterally arranged domes 14 to diagonal positions with respect to the checkerboard arrangement of domes, a clearance is provided for the adjacent corner region of one of the domes of the group to the end that this corner region is free to pass downwardly below the level of the cradle member. In FIG. 1, one of the domes 14 is shown as assuming a fully released condition wherein it is disposed below the level of four of the cradle members 16, each of which has been turned on its respective shore through an angle of 45. It is to be noted at this point that even though four of the cradle members 16 have been thus rotated through an angle of 45, these four cradle members still maintain their underlying relationship with all of the adjacent domes. It is also to be noted that although the dome 14 has been released by the four angularly disposed cradle members 16, the extreme upper ends of the four shores l2, i.e., the tubular housings 70 and the associated filler plates 18, continue to support the ceiling slab S, the housing thus serving as upward extension of the tubular bodyv portions 36 of the shore heads 34.

After all of the domes 14 have been removed from the installation, the various shores may be allowed to remain in place until the concrete of the slab S has fully hardened. Meanwhile, the domes which have been removed from the installation are immediately available for reuse in the same installation or in a different installation.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention. For example, if desired, the elevation post 62 of the shore 12 may be dispensed with, in which case, no initial adjustment for leveling the various domes 14 may be made from above dome level, the threaded engagement between the tubular body portion 36 and the post section 38 of the shore head 34 being relied upon for dome leveling purposes.

Having thus described the invention what I claim as new and desire to secure by letters patent is:

1. In a concrete ceiling slab form installation, in combination, a plurality of generally coplanar rectangular slab-supporting domes arranged in checkerboard fashion and providing groups of domes which are disposed in horizontal contiguous quadrilateral relationship with converging corner regions, each dome being in the form of an integral inverted pan having a flat horizontal rectangular top wall, a continuous outwardly sloping sidewall comprised of four trapezoidal wall panels, a lower substantially continuous, generally rectangular, horizontal rim flange projecting outwardly from the lower rim of said sidewall, and a continuous vertical apron flange depending from the outer edge of said rim flange, the corner regions of the rim flange of each dome being truncated so that each of said groups defines a central rectangular void which interrupts the surface continuity of said rim flange, and a vertically disposed dome and slab-supporting shore cooperating with the converging corner regions of each of said groups, each shore comprising a post having its lower end resting on a foundation surface, a cradle member mounted on said post in the upper region thereof for rotation about the vertical axis of the post, said cradle member including a pair of ledgelike supports projecting laterally and radially outwardly from the post in opposite directions, said cradle member being movable between one angular position wherein said ledgelike supports extend in a seam line direction with respect to the checkerboard arrangement of domes and serve to underlie and support the converging corner regions of all of the domes of said group with the various apron flanges resting in on-edge fashion on said ledgelike supports, and another angular position wherein said ledgelike supports extend in a diagonal direction with respect to said checkerboard arrangement and are withdrawn from their underlying and supporting relationship with respect to the corner region of at least one of the domes of said group, and a rectangular filler plate disposed on the upper end of said post and projecting into the void that is established by said groups of domes in sealing relationship with respect to the marginal edges of the latter.

2. [n a concrete ceiling slab form installation, the combination set forth in claim 1, wherein said rim flanges have their corner regions truncated on a 45 bias so that the central voids established thereby are of square outline, the combined radial extent of each pair of ledgelike supports is greater than the extent of one side edge of a central void, and the transverse width of each ledgelike support is less than the extent of said one side edge, whereby, when said ledgelike supports extend in a diagonal direction with respect to the checkerboard arrangement of domes, they are withdrawn from their supporting relationship with respect to the converging corner regions of a pair of diagonally aligned domes.

3. In a concrete ceiling slab form installation, the combination set forth in claim 1 and wherein said cradle member, in addition to being rotatably mounted on said post, also is vertically slidable on the latter between a raised position wherein said filler plate projects into said void, and a lowered position wherein said filler plate is withdrawn from said void to permit rotation of the filler plate.

4. In a ceiling slab form installation, the combination set forth in claim 3 and wherein said ledgelike supports are each provided with upstanding dome-retaining posts, and the apron flange of each dome normally encompasses one of said ledge supports.

5. In a concrete ceiling slab form installation, the combination set forth in claim 4, wherein said cradle member is in the form of a tubular sleeve which loosely encircles the post and is both slidable and circumferentially rotatable thereon, the ledgelike supports project radially outwardly from said sleeve, the post is provided with a fixed reaction shoulder below the level of the sleeve and upon which the lower edge of the sleeve is adapted to rest to determine the lowered position of the cradle member, and said shore is further provided with a remova' ble reaction member adapted for interpositioning between the lower edge of said tubular sleeve and the reaction shoulder and upon which the lower edge of the sleeve is adapted to rest to determine the raised position of the cradle. 

1. In a concrete ceiling slab form installation, in combination, a plurality of generally coplanar rectangular slab-supporting domes arranged in checkerboard fashion and providing groups of domes which are disposed in horizontal contiguous quadrilateral relationship with converging corner regions, each dome being in the form of an integral inverted pan having a flat horizontal rectangular top wall, a continuous outwardly sloping sidewall comprised of four trapezoidal wall panels, a lower substantially continuous, generally rectangular, horizontal rim flange projecting outwardly from the lower rim of said sidewall, and a continuous vertical apron flange depending from the outer edge of said rim flange, the corner regions of the rim flange of each dome being truncated so that each of said groups defines a central rectangular void which interrupts the surface continuity of said rim flange, and a vertically disposed dome and slabsupporting shore cooperating with the converging corner regions of each of said groups, each shore comprising a post having its lower end resting on a foundation surface, a cradle member mounted on said post in the upper region thereof for rotation about the vertical axis of the post, said cradle member including a pair of ledgelike supports projecting laterally and radially outwardly from the post in opposite directions, said cradle member being movable between one angular position wherein said ledgelike supports extend in a seam line direction with respect to the checkerboard arrangement of domes and serve to underlie and support the converging corner regions of all of the domes of said group with the various apron flanges resting in on-edge fashion on said ledgelike supports, and another angular position wherein said ledgelike supports extend in a diagonal direction with respect to said checkerboard arrangement and are withdrawn from their underlying and supporting relationship with respect to the corner region of at least one of the domes of said group, and a rectangular filler plate disposed on the upper end of said post and projecting into the void that is established by said groups of domes in sealing relationship with respect to the marginal edges of the latter.
 2. In a concrete ceiling slab form installation, the combination set forth in claim 1, wherein said rim flanges have their corner regions truncated on a 45* bias so that the central voIds established thereby are of square outline, the combined radial extent of each pair of ledgelike supports is greater than the extent of one side edge of a central void, and the transverse width of each ledgelike support is less than the extent of said one side edge, whereby, when said ledgelike supports extend in a diagonal direction with respect to the checkerboard arrangement of domes, they are withdrawn from their supporting relationship with respect to the converging corner regions of a pair of diagonally aligned domes.
 3. In a concrete ceiling slab form installation, the combination set forth in claim 1 and wherein said cradle member, in addition to being rotatably mounted on said post, also is vertically slidable on the latter between a raised position wherein said filler plate projects into said void, and a lowered position wherein said filler plate is withdrawn from said void to permit rotation of the filler plate.
 4. In a ceiling slab form installation, the combination set forth in claim 3 and wherein said ledgelike supports are each provided with upstanding dome-retaining posts, and the apron flange of each dome normally encompasses one of said ledge supports.
 5. In a concrete ceiling slab form installation, the combination set forth in claim 4, wherein said cradle member is in the form of a tubular sleeve which loosely encircles the post and is both slidable and circumferentially rotatable thereon, the ledgelike supports project radially outwardly from said sleeve, the post is provided with a fixed reaction shoulder below the level of the sleeve and upon which the lower edge of the sleeve is adapted to rest to determine the lowered position of the cradle member, and said shore is further provided with a removable reaction member adapted for interpositioning between the lower edge of said tubular sleeve and the reaction shoulder and upon which the lower edge of the sleeve is adapted to rest to determine the raised position of the cradle. 